Diagnosis and Tests for Upset Stomach (Gastritis) in Dogs

Initial Evaluation

Most dogs with gastritis are brought to the veterinary clinic because they either had a very sudden onset of profuse vomiting, or they have been vomiting off-and-on for several weeks. The most important part of the veterinarian’s initial evaluation is getting the dog’s complete history from its owner, including its health background, diet, eating/chewing habits, access to garbage and household chemicals, free-roaming activities and whether it is on any oral medications. Of course, the discussion will include its current symptoms – that is, exactly why the owner brought the dog to the veterinarian at this point in time. The initial medical assessment usually will conclude with a thorough physical examination, during which the veterinarian will look in the patient’s mouth and gently palpate (press and feel) its neck, chest and belly and flank areas.

In many cases – in fact, probably most of the time – the underlying cause of gastritis will never be identified. This is called “idiopathic gastritis.” “Idiopathic” means “of unknown origin.” This term is used in connection with a host of diseases and disorders, including gastritis. It indicates that doctors, scientists and other medical personnel have not yet figured out the precise cause of the condition it is being associated with.

Diagnostic Procedures

The initial veterinary evaluation rarely discloses a specific cause of the dog’s vomiting and abdominal discomfort. The diagnosis typically is made by ruling out possible causes of the dog’s condition. This is called making a diagnosis of exclusion. In other words, the veterinary team will try to rule out as many potential causes of the dog’s symptoms as they can, to narrow down the range of what might be responsible for its discomfort.

Inflammation of the stomach can be caused by many different things. These include obstruction by a foreign object, parvoviral infection, distemper, bacterial overgrowth, uremia/kidney disease, diabetes, hypoadrenocorticism (Addison’s disease), hepatic (liver) disease, electrolyte imbalances, pancreatitis and stress, among a number of other things. Most cases of gastritis occur after a dog eats something that it shouldn’t. Unfortunately, “dietary indiscretion” and “garbage gut” are phrases that veterinarians and dog owners are all too familiar with. When a dog is vomiting or showing other signs of abdominal discomfort, its veterinarian may recommend withholding food for a short period of time, to see if the situation improves. Depending on the severity of vomiting, water may also be withheld, or only offered periodically in small amounts. Anti-inflammatory and/or antibiotic medications may be administered under a veterinarian’s supervision, even before the reason for the gastrointestinal distress is identified, to see whether the dog responds to treatment. If the dog improves with these noninvasive treatments, then the problem probably was caused by the dog swallowing something that didn’t set well in its stomach or by a bacterial infection, and further treatment will likely not be necessary.

In severely acute or chronic cases of gastritis that don’t respond to the initial diagnostic efforts, the veterinarian will want to perform routine blood and urine tests and abdominal radiographs (X-rays). She probably will also recommend taking a biopsy sample of a few different areas of the stomach lining in an attempt to find the cause of the condition. Blood tests are extremely useful to assess the dog’s overall health and to rule out systemic illnesses such as parvovirus, distemper, diabetes, endocrine disorders, liver disease and kidney disease. Routine blood work also can reveal electrolyte and hormonal abnormalities and anemia. Radiographs, and ultrasonography, can help the veterinarian assess whether a mass or foreign object is blocking some part of the dog’s gastrointestinal tract and whether the stomach lining is thickened, distended or inflamed. Special contrast studies can be done to detect obstructive foreign bodies, gastric outflow obstruction, defects in the stomach wall or delayed emptying of stomach contents. This procedure involves passing special radiopaque material, such as barium, through the dog’s mouth into its digestive tract. The movement of that contrast material can be followed on a monitor screen in real-time. Any blockage, or abnormally long passage of ingesta from the stomach into the small intestine, usually will be obvious from this study, although the exact cause of those conditions still may not be clear.

The veterinarian can take tissue biopsies using an endoscope, which is a wand-like instrument with a camera at its tip that is passed through the dog’s mouth, down its throat and esophagus and into its stomach. Various accessories can be attached to the endoscope that let the veterinarian move it around and rotate it, visualize all areas of the stomach lining and pinch off samples of tissue that looks red, inflamed, lumpy, bloody or otherwise abnormal. Biopsy samples usually will be taken even if the gastric lining looks normal. The samples will be sent to a pathology laboratory, processed and examined under a microscope through a procedure called “histopathology.” They also may be cultured, which is a process that involves growing bacterial, viral or other infectious organisms in special culture media. Heavy sedation is necessary for this procedure.

Other possible diagnostic tools are fecal evaluation (to look for the presence of internal parasites which might be causing the dog’s symptoms), and exploratory abdominal surgery, which usually is a last diagnostic resort.

Special Notes

Gastritis is a general term for inflammation of the lining of the stomach. It is important to identify the cause of gastritis – or at least to rule out as many potential causes as possible – so that the dog’s treatment can be tailored appropriately.